Just a hyped up commercialised style for people who want to throw their money away on memberships.
(But look the cats tits in their new t-shirt and prefect moves with a non resisting partner?)
Or a genuine bad-ass street realistic system that focusses on training that isnt 'sport' orientated?
Anyone trained in it with an opinion on it?
Wasn't it developed by the Israeli military?
Replace the name 'Krav Maga' in your title with Karate, Wing Chun, TKD, or any other martial art and the rest of the thread would still make a sensible and relevant question.
The fact is that it's not the style that's at fault (see Machida, Nelson, etc. for how Karate can be effective) it's the way it's taught and trained. As you've noted, no martial art can be trained effectively without resistance; it's akin to practising football penalties without a goalkeeper there. You need to know that you can land strikes or pull off subs on someone who is really trying to stop you or you'll not really know that it's effective. Moreover, you need to know that you can do this while they are not just resisting, but trying to take your head off. If any 'fighting' style is not trained this way then it isn't being trained effectively or realistically. You don't knwo that the moves will work and, since you're not scared of getting hurt, you don't know how you'll deal with the adrenaline.
The bigger problem for Krav Maga (and any other 'street' based style) is that you can't realistically train gouging someone's eyes out or snapping their knee cap. You can go through the motions, but that's not the same thing (any more than me showing you a sub in MMA means I could actually pull it off; in theory I can pull off flying traingles, but I doubt that I'm really going to do it when you're trying to stop me!).
So to answer your question, you can't really slate the whole style of Krav Maga. You'd have to look at the school that's teaching it and how they're doing it. However, I don't think it would be unfair to say that most Krav Maga places in this country are not teaching anything that effective for three major reasons:
1, The majority of people who turn up to a Krav Maga class want to feel like they can fight but don't want to get hurt in the process of learning, which, as mentioned before, is just not going to work. This is true of most TMAs.
2, As a result the way most Krav Maga schools will make their money is by pandering to this crowd and teaching them watered down crap in a watered down way. Oh, and selling lots of t-shirts.
3, Even the schools that try to teach it effectively and realistically are going to struggle (for financial reasons if nothing else) because you cannot realistically train smashing people's bones and killing them. Even if you could, how often are people ever going to encounter a situation in real life where they will do this (and not end up in prison). This is arguably why styles designed for military use, like Krav Maga, should not really be taught to civilians anyway.